Authorities arrested Douglas Ellison, 34, and charged him with robbery and resisting arrest.

Police said Ellison held up the Wilson Street branch just after 4 p.m., demanding money and telling the clerk he was armed with a gun. They said Ellison fled with an unknown amount of cash before officers arrived.

Detectives reviewed surveillance video and stopped a vehicle matching the footage, which led them to a Wilson Street address where Ellison was arrested.

According to police, Ellison is already serving time for a prior armed robbery and had been serving the end of his sentence at the Calumet House on Lowell Street, a transitional housing unit.